The present invention relates to plastic film wound on a core, and more particularly it relates to apparatus and method for forming a rolled tab in the tail end portion of the plastic film and a roll of plastic film having a rolled tab.
Commercial plastic film for consumer use is customarily manufactured by winding plastic film on a core and packaging the roll in a dispensing container for retail sale. The plastic film has a tail end portion extending around the surface of the roll and terminating at a tail edge. The plastic film is customarily manufactured with a clinging or adhesive surface to enhance its function as a wrapping material such as, for example, Saran Wrap films commonly used as household wrappings. Because of the clinging characteristic of the film, the tail end portion sticks to the surface of the roll making it difficult to identify and grasp the tail edge in order to separate the tail end portion from the surface of the roll without tearing it. The need for finding the tail edge of the film on the roll of plastic film and starting to unwind it without tearing has been long recognized, particularly with plastic film having considerable cling. Hence, roll-starting features have been used in the past to facilitate peeling the tail end portion of the film away from the surface of the roll.
One technique employed prior to the present invention involved applying a foreign substance to the tail end portion of the plastic film to prevent sticking, such as, for example. starch dust or wax. Such foreign substances or coatings, however, are difficult to apply to the film at normal conveyor speeds and do not survive extreme warehouse storage temperatures. Solvents have also been applied to the tail end portion of the film to induce curling in the tail end portion. The solvents, however. are volatile and difficult to use in-line. The most common technique involves the use of heating apparatus located in-line to emboss a pattern in the tail edge of the film to distinguish it from the rest of the film and reduce sticking of that portion to the surface of the roll. Embossing the plastic film at high conveyor speeds, however, is difficult because the plastic film is relatively fragile and susceptible to breaking upon repeated contact with the embossing plate. Furthermore. the embossed portion of the film must be precisely synchronized with cutting apparatus that forms the tail edge in the embossed portion of the film. Maintaining adequately precise temperature control is also difficult because the film will tear if the plate is too hot and will not be sufficiently embossed if the plate is too cold.
Accordingly, there is a need for a roll-starting feature and, more specifically, one that is capable of being formed in-line without the application of a foreign substance or heat and without the need for complex electronic synchronization.